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Full text of "The Cambridge Natural History"

nountain. Externally it is something like the Pikas/since it
las no tail visible. The ears, too, are short, and the Mn4-le%&-
iomparativeiy short. The skull is very like that of the Rabbit;
Dut in other osteological details it is aberrant. Thus the clavicle
is quite complete, and only six ribs articulate with the sternum,
instead of the seven that we find in the Babbit.
Fam. 2. Lag-omyidae.—The animals of this family are smaller
bhan the Hares and Habbits; they have short Vole-like ears and
QO external tail. The limbs also appear to be shorter. As there
LS but a single genus, the characters of the family may be de-
scribed in connexion with those of the genus, which is known as
Lagomys (apparently more correctly OcJiotona}. Of this genus
there are about sixteen species, which are mainly Asiatic; one
species extends its range into Eastern Europe, and three are
North American.
The skull has not the supra-orbital grooves of the Rabbits,
a,nd has a well-marked backward process of the zygomatic arch.
There are eighteen dorsal vertebrae. The molars and premolars
are five.
The vernacular names of " Pika " and " Piping Hares " have
been applied to the members of this genus, the latter on account of
their peculiar call. They live among rocks in companies and they
burrow. They are usually found at considerable altitudes: thus
L. roylei, the " Himalayan Mouse Hare," is found at elevations
as high as 16,000 feet; while L. ladacensis gets even higher,
19,000 feet having "been recorded. With the habits of a Marmot,
so far as concerns living in burrows and afc great altitudes, the
animals of this genus, with their squat form and short ears, are
not unlike those animals. In the past this genus occurred more
generally over Europe. Species from Miocene beds have been
met with in England, France, Germany, and Italy.
Fossil Rodents.—Quite a large number of existing genera of
Rodents are known from even the earlier strata of the Tertiary
period. The Squirrels (and even the genus Sciurus itself) occur in
the Upper Eocene. So, too, do the genera Myoxiji£y and (in South
America) Lagostomus. Spermophilus, Acomys> Hystrix, Lagomys,
Lepus, Hesperomys are known from. Miocene rocks. 2thizomy&,
Castor, Cricetns, Mus, Hicrotus, and some others appear to have
originated so far as we know in the Pliocene, while a still
^oe r»f A-K-istiner crenera are Pleistocene. It is interesting